Since averaged evoked potentials to peripheral nerve stimulation which arise in the dorsal roots (cauda equina) and spinal cord can be recorded with surface electrodes placed over the human spine, it seems that this technique has potential value as an investigative method and, possibly, as a diagnostic aid in the assessment of patients with spinal cord pathology. In this study, the evoked spinal response recorded in normal adults and in adult patients with various types of spinal cord pathology will be compared. The maturation of this response will be studied and the response recorded in premature infants, term infants and children with spinal cord pathology will be compared with that recorded in normals of similar age. Evoked spinal responses will be recorded during laminectomy to determine whether this technique is useful as an aid in establishing prognosis in these patients. Studies directed toward learning more about the afferent system which mediates this response will be undertaken. Additionally, an attempt will be made to determine whether evoked responses can be recorded from surface electrodes placed over the human spine in response to visual and auditory stimulation.